In a cellular or other network, some methods for a device to access services require the device to have a subscriber identity, typically encoded within a secure environment such as a UICC, SIM or embedded SIM, for example. The subscriber identity may be given provisioning data (usually in the form of cryptographic material), which allows the device to subscribe to one or more services. Subscription may involve the addition of the subscriber identity to a subscriber profile repository or subscriber list held by a subscription manager. The addition of the subscriber identity to such a repository can be dependent on the device presenting suitable provisioning data, which may be checked and validated. Providing the device (or the UICC, SIM or embedded SIM) with these provisioning data is known as provisioning the subscription of a service.
Existing SIM cards (UICC) may be personalised individually with unique keys and identifiers at a secure personalisation centre. This may be operated by a SIM vendor or manufacturer like Gemalto or Giesecke and Devrient.
The SIM cards are then distributed from that centre either to operator warehouses, or increasingly in the case of machine to machine (M2M) devices, directly to a modem or whole device manufacturer (OEM) for integration as a component part. The OEM then has to personalise the rest of the device e.g. with a flash image, unique device ID, MAC address and possibly other keys.
This process has several problems:                Each unique personalization step adds costs;        There is a “detour” from the original chip maker (a party like Infineon or NXP) via the SIM personalization centre before the UICC is shipped to the OEM;        The UICC is constrained in terms of form factor: e.g. it must be a dedicated “chip” with its own packaging, defined contacts and size. This can create some issues in terms of size of M2M equipment, and durability of the UICC in a long-lived device or in a difficult environment (SIM card may be shaken lose, contacts may overheat, freeze, become too moist etc.) While specially packaged UICCs exist (machine form factor), these are more expensive than conventional SIM card form factors, and so are harder to apply to low cost devices.        With a reduction in device cost the SIM can become a disproportionate share of the total device cost.        
Many types of devices may be granted access to a mobile network as long as the network access credentials (also known as AKA credentials) are valid. These credentials need to be stored in a “secure execution environment” (typically a SIM card) to prevent tampering and cloning.
However, if a mobile operator's subscription key is negotiated remotely, for example via a Diffie-Hellman key exchange, rather than loaded at manufacture of the device, then it can be difficult for the mobile operator to determine whether the resulting key is being stored in a Secure Execution Environment (like a SIM card) since authentication of the device may not be possible. These concerns are sufficiently serious to rule out an “anonymous” Diffie-Hellman approach.
One way to ensure provisioning of AKA credentials to the right target requires the device being equipped with identities that cannot be usurped. It is therefore important that each device is equipped with unique identification, and that there is an assurance that this unique identification cannot be modified without strong authorization.
If asymmetric cryptography is chosen then each device must be provisioned with a unique public-private key pair.
Some entity must therefore take responsibility and some liability for the security of the device. This “liable representative” may provide a trust anchor to any entity such as the mobile network operator (MNO) that needs to verify the identity of the device.
The Machine Form Factor SIM (MFF1, MFF2) addresses some of the form factor issues, but does not address the cost and logistic issues. Furthermore, it is more expensive than typical SIM card form factor.
In 2008, Oberthur and Wavecom (later acquired by Sierra Wireless) proposed a solution called “inSIM” which would allow the SIM card to be placed inside another chip package (the baseband processor). However, the solution did not meet operator security requirements, as the operator credentials would need to be provisioned to the “inSIM” at an insecure location (OEM production line).
Recent approaches to embedded SIM (eUICC standardization efforts in GSMA and ETSI SCP, Vodafone SOBE project) allow an operator subscription to be updated remotely on the UICC. However, these approaches still require unique initial secrets to be loaded to each UICC, so do not avoid the need for a smart card personalization centre.
Further, the UICC needs to be loaded with an initial IMSI/Ki and profile (a so-called “provisioning subscription”) in order to connect to a mobile network and download a permanent subscription.
U.S. Pat. No. 8,589,689 describes over-the-air provisioning of authentication credentials at an access device via a first access system (e.g. CDMA), wherein the authentication credentials are for a second access system (e.g. 3GPP) lacking an over-the-air provisioning procedure. Whilst, this enables access to a mobile network, it doesn't allow devices to be provisioned by external entities in a secure manner.
Furthermore, a motivation for the use of smart cards as “Secure Execution Environments” is to avoid problems with untrusted (or rogue) subscribers. However, M2M will often use trusted business partners of a network operator as subscribers, or otherwise use large businesses with a reputation to protect. Such organisations are not likely to deliberately violate terms of service (via cloning etc.), or run up big bills without paying. A business partner may offer (or wish to use) an alternative to a smart card as a way of storing an operator's subscription key (K), either on the grounds of cost, or size, or durability.
In this case, the partner may be confident enough to accept the liability for bills in the case of a leak/clone of the subscription credentials.
Note that even with trusted business relationships, one particular challenge to consider that devices may go through distribution channels which aren't entirely trusted. If key material loaded at device manufacture is not sufficiently protected, then an individual, such as a shop assistant (for instance), could extract it and use it to discover the final key material.
In some M2M scenarios, a technician needs to configure the device prior to activating it for operations. A known solution would be to provide a batch of SIM cards to the technician to insert into the devices.
However, there is considerable complexity and risk of carrying a plurality of SIM cards. If the technician has to take them to an external or insecure environment such as a public place, then a thief could attempt to steal from the plurality or stack of SIM cards. If the theft remains unnoticed for several days, then it may have repercussions. The SIM card may be used in an unintended device, incur data and/or voice charges at the M2M customer's expense, or provide faulty information (e.g. false location information to a vehicle tracking service). Additionally, the technician might himself be a thief, or co-operating with the thief.
There is also the risk that the technician does something wrong when configuring the device and in particular when activating the subscription and “binding” it to a particular device. This could either be a human error or attempt to tamper with the credentials used to set up the network access credentials. There is a particular risk of error if the IMSI-IMEI binding was set up before insertion of the SIM card, since the technician might accidentally insert the SIM card in the wrong device. Or even if the binding is set up during or after activation (via a portal) then the SIM card might now be bound to the wrong device.
For technician provisioning, one direct countermeasure to the risks could be for any SIM card to be activated only after being inserted in the target device. The authorization of the activation may be a combination of things, e.g. the technician being authenticated to a Device Management (DM) portal, the SIM being authenticated by the mobile network, the device being authenticated by the DM portal, the device having successfully reported which SIM is currently inserted in it.
A further countermeasure could be to limit what the SIM can do when activated, e.g. it may be prohibited from making voice calls, or is only allowed to transmit small amounts of data, or only allowed to transmit to designated addresses (M2M servers) rather than the wider Internet.
Another useful countermeasure could be “binding” an IMSI (SIM identifier) to an IMEI (device identifier). This may ensure that a SIM can only be used within a target device. For example, if the SIM is placed in a different device, then the alternate IMEI is reported to the mobile network's HLR, which detects that it is not the intended device. That can lead to barring or temporarily suspending the subscription. A more complicated solution (but one that may protect against a faked IMEI) is a secure channel between the SIM card and the target device.
Cost reasons are a major driver in M2M. Security requirements may be beyond the above solutions or potential solutions and may also increase costs and decrease flexibility. Cheaper solutions to conventional SIM cards having full flexibility across a whole range of low-cost devices are also desirable.
Therefore, there are required a method, system and apparatus that overcomes these problems.